Many formulations such as inks, paints, mill-bases and plastics materials require effective dispersants for uniformly distributing a particulate solid in an organic medium. The organic medium may vary from a polar to non-polar organic medium. Dispersants containing terminal basic groups such as poly(lower alkylene)imine chains are well known and are generally prepared by reaction of the polyimine with polyester chains containing terminal acid groups, the reaction results in a mixture of amide and salt forms.
U.S. Pat. No. 4,224,212 discloses dispersants comprising a polyester derived from a hydroxycarboxylic acid with at least 8 carbon atoms reacted with a poly(loweralkylene)imine. The dispersants are effective in non-polar medium such as aliphatic solvents and plastics. However, the dispersants have limited performance in a polar medium.
European Patent Application EP 208041 A discloses dispersants with a polyester derived from ε-caprolactone reacted with a poly(loweralkylene)imine. The dispersants are particularly effective in more polar medium such as ketones and esters. However, the dispersants have limited performance in a non-polar medium.
U.S. Pat. No. 4,865,621 discloses motor fuel compositions comprising the reaction product of a dibasic acid anhydride, a polyoxyalkylene monoamine and a hydrocarbyl polyamine having a number average molecular weight of up to 1343.
However, U.S. Patent Application 60/637937 and PCT. Application WO 05/010109 A discloses dispersants with acceptable performance in a polar and a non-polar organic medium. However, the dispersants have poor flocculation resistance in reduced shades (coloured paint being let down into a white base paint) and/or storage stability in media, such as millbases and paints.
Therefore, it would be advantageous to have a dispersant with acceptable performance in both a polar and a non-polar organic medium and said dispersant having acceptable flocculation resistance and/or storage stability.